Electrical switch of the fluid flow type



May 10, 1938. M. NIPPOLD ELECTRICAL SWITCH OF THE FLUID FLOW TYPE FiledJune 18, 1937 2 Sheets-Sheet l Fig-2a INVENTOR Max Nippold X 21 A ORNEYFig. 2

May 10, M N|PPOLD ELECTRICAL SWITCH OF THE FLUI D FLOW TYPE Filed June18,1937, 2 Sheets-Sheet 2 INVENTOR Max Ni ai/oold #aag". I

A TORNEY Patented May 10, 1938 UNITED STATES PATENT OFFICE nmc'rmcanswrrcn or was room now I mm tion of New York Application June 18, 1931,Serial No. 148,996 In Germany June 24, 1936 1 Claim. (cl. zoo-152) Thepresent invention relates to electrical switches of the fluid flow type,and especially to switches of this type having asealed envelope whichconsists almost exclusively of metal.

A particular object of the invention is to provide an improved switch ofthe fluidflow type. Another object of the invention is to simplify theconstruction of such switches. Still other objects and advantages of myinvention will appear from the following detailed specification or froman inspection of the accompanying drawings.

' The invention consists in the new and novel switch structure, ashereinafter set forth and claimed.

The somewhat fragile nature of the glass envelopes of the mercuryswitches which are now in extensive use has led to the development ofswitches in which metal is substituted to a large extent .for theseenvelopes, switches it ,is, of course, still necessary to retainsuficient glass to insulate the separate contacts of theswitch. Asheretofore developed this has resulted in a seal of comparatively largediameter. I have now discovered that by a novel structure of myinvention these switches may be made of substantially all metal, withonly the use of a small glass head as insulation. This facilitates themanufacture of these switches in very small sizes, as compared to priorswitches, and also affords numerous other advantages.

The invention is illustrated by means of several examples. in theaccompanying drawings, in which -Figure 1 shows the the new switch,

Figures 2 and 2a show the introduction of the electrode through amaterial with coemcient of expansion which approximately agrees withthat o l Figures 3 and 4 show'these switches in closed and open circuitposition, respectively,

Figure 5 shows a be her shaped switch with welded cover,

Figure 6 shows a tube welded cover, r Figure 7 shows a tube withconstructions ready to be cut apart to form switch bodies,

shaped switch with "Figure 8 shows a switch whose inlead is in- .sertedinsulated through the constriction at one end, while the otherconstriction iswelded shut,

and

Figure 9 shows a switch with an enclosed steel sphere which is adaptedfor magnetic operation. According to the invention as shown in Figure1,-fa projection b is provided in a closed metal In each of these ring hand theplatinum coating i applied thereto,

tube a. In this metal tube, which is made of a material which is notattacked by the liquid, e. g. steel where mercury is used as the switchliquid, there is placed the switch liquid c. As the switch liquidmercury, or, where desired, as where the 5 switch may encounter highambient temperatures, potassium-sodium, gallium etc. is used. The metaltube (4 serves as one contact, while the other contact is introduced asan inlead wire d through a suitable insulatlng'bead e of glass or thelike. So-that the switch liquid will not be contaminated or oxidized, avacuum is produced in the tube, or preferably the tube is filled with aprotective gas, such as nitrogen, hydrogen, or the like, at anydesired-pressure, up to several atmospheres. In general, however, normalatmospheric pressure is chosen. The evacuation hole I at the end of thetube is closed after this process, for instance by scaling in a pin g orafilxing a sphere.

The current capacity of sucha switch is determined by the thickness andresistance of the inlead d, the quantity of the liquid c and the contactresistance between the metal and the liquid. As this contact resistance,suchas that between iron and mercury, for instance, is extremely high, acoating of platinum is preferably provided on the end of the inlead dand on the tube (1 around the glass bead e. Thiscoating is produced inany suitable manner, as by melting it on or by chemical orelectrolytlcal means.

The voltage which the switch is capable of handling is determined by thedistance between simplest possible form .of

the'inlead d and the metal casing, i. e. by the size of the glass beadc. This voltage capacity is, of course, easily altered by varying thisdistance. Besides this glass insert, according to the invention aninsert of porcelain or micalex can also beused, which is particularlysuitable for the switching of high frequency currents. 40

In the foregoing it is assumed that the switchenvelope a is made of ametal, such as a special iron alloy (e. g. fernico), which haspractically the same coeflicient of expansion as glass. These alloys,however, are relatively expensive, and hence the insertion of inleadsaccording to the invention is preferably accomplished by means of a ringit of this alloy which is welded into an envelope of any metal which issuitable for use with the switch'fluid, as shown in Figure 2. Or, as isshownin Figure 2a, magnified, this ring it is sealed on by an externalweld. 'I'he latter method of construction has the advantage that thebeaded glass inlead d can be fused to the and off positions.

after which this complete assembly is welded into the switch tube as astopper after the switch liquid has been introduced, the tube evacuated,and the protective gas introduced. A special closing by pin or sphere isthus made unnecessary Figures 3 and 4 show such -material, and theswitch liquid 0. The disc m is in some cases made of a special ironalloy or. oi steel to which glass can be directly fused. in which case,as in Figure 2, the ring-glass seal is welded on. If the glass seal ismade directly on the disc m without a ring, then a filling hole must beprovided, which is sealed by a sphere n.

Figure 6 shows a construction similar to that of Figure 5, in whichhowever the envelope 1 is more tube shaped. With such a switch theswitching can be accomplished by turning as well as by tilting. v

Where a very large number of these switches are desired it is convenientto provide a seamless steel tube 0 with constrictions p, as shown inFigure '7. This tube is then cut through at these constrictions and theprotective gas, switch liquid, inlead with glass seal, and finally themetal ring are inserted at one end as-shown in Figure 8.

The other constriction is then sealed directly or a switch in the on bymeans of a sphere n or the like, with the aid of welding heat.

Figure 9 shows yet another form with bent tube 0 in which another steelsphere q is introduced.

-When the coil 1- which is placed about the middle of said tube ismomentarily energized this sphere is attracted and rolls to theother endof said 'tube, whereupon the switch,- which is freely movthereof it isto be understood that it is not limited th ereto, but that variousomissions, substitutions and changes, within the scope of the appendedclaim, may be made therein without departing from the spirit of theinvention.

What I claim as new and desire to'secure by Letters Patent of the UnitedStates, is:-

A fluid flow switch comprising a metal con-' tainer containing aconducting fluid, said container being of a metal which is substantiallyunaflected by said fluid, an opening in said container within which iswelded a ring of a diiferent metal which likewise is unaflected by saidliquid and whichhas a coeflicient of expansion comparable with that ofglass, a glass-beaded inlead fused into said ring, and a platinumcoating on said inlead and on said ring, said liquid being suflicient toclose an electrical circuit between the coated areas on said inlead andsaid ring.

